1. Field of the Invention
The present invention generally relates to a non-contact IC card reader/writer device, a non-contact IC card, an input device, and a method of calculating the location of a non-contact IC card, and more particularly, to a non-contact IC card reader/writer device that performs communication by means of data strings produced by amplitude modulation of each carrier wave generated through antennas.
2. Description of the Related Art
Referring to FIGS. 1 through 5, a conventional non-contact IC card will be described below. FIG. 1 is a block diagram of a conventional non-contact IC card reader/writer device 600 and a non-contact IC card 610.
The non-contact IC card reader/writer device 600 includes an external interface unit 601, a control unit 602, and a transmission/reception block 603. The control unit 602 controls the entire non-contact IC card reader/writer device 600, and performs data transmission and reception with a host device (not shown) via the external interface unit 601. The transmission/reception block 603 includes an antenna 604, a transmission unit 605, and a reception unit 606.
The antenna 604 is a coil antenna, for example, and performs carrier wave transmission and reception with the non-contact IC card 610. The transmission unit 605 modulates transmission data supplied from the control unit 602, and amplifies the modulated signal. Based on the amplified output signal, alternating current is supplied to the antenna 604 to generate an electromagnetic wave. The reception unit 606 amplifies each signal received through the antenna 604, and demodulates the amplified signal to obtain reception data. The reception data are outputted to the control unit 602. Data communication through amplitude modulation of each carrier wave is performed between the non-contact IC card reader/writer device 600 and the non-contact IC card 610.
FIG. 2 illustrates a reception wave in the non-contact IC card 610 and the non-contact IC card reader/writer device 600. As shown in FIG. 2, the non-contact IC card reader/writer device 600 and the non-contact IC card 610 rectify the alternating-current component of each reception wave to a direct-current component, and determine a data string from the intensity of the direct-current component. In a communication operation from the non-contact IC card reader/writer device 600 to the non-contact IC card 610, each carrier wave is amplified and modulated in accordance with the bit order of data to be transmitted.
FIG. 3 illustrates a reception waveform in the non-contact IC card 610. The non-contact IC card 610 determines each data string from the intensity of voltage after rectification. In a communication operation from the non-contact IC card 610 to the non-contact IC card reader/writer device 600, an internal logic switch that will be described later is switched on and off, in accordance with the bit order of data for transmitting each carrier wave received from the non-contact IC card reader/writer device 600.
FIG. 4 illustrates communication between the non-contact IC card reader/writer 600 and the non-contact IC card 610. As can be seen from FIG. 4, the non-contact IC card reader/writer device 600 and the non-contact IC card 610 have loop-coil antennas 604 and 611, respectively. The non-contact IC card 610 includes a logic switch 612 that can change load capacities of the loop-coil antenna 611. When data transmission is performed, the logic switch 612 is switched in accordance with the data string. Data transmission and reception are performed through electromagnetic coupling between the loop-coil antenna 604 of the non-contact IC card reader/writer device 600 and the loop-coil antenna 611 of the non-contact IC card 610. The loop-coil antennas 604 and 611 are used in both transmission and reception.
FIG. 5 illustrates changes in a carrier wave in the non-contact IC card reader/writer device 600. As the logic switch 612 of the non-contact IC card 610 is switched on and off to change load capacities, the non-contact IC card reader/writer device 600 can monitor the changes in a carrier wave shown in FIG. 5. The non-contact IC card reader/writer device 600 determines the data string from the voltage intensity, and thereby performs data communication.
As another conventional technique, Japanese Unexamined Patent Publication No. 2000-46939 discloses a wireless card location detecting system. This wireless card location detecting system includes: a wireless base station that transmits electric waves; a wireless card that receives each of the electric waves and measures the electric field intensity; a control device; and a database that stores electric field intensity distribution data. The wireless card divides electric waves into vertical polarized wave components and horizontal polarized wave components, and measures the electric field intensities of those components. The control device compares the measurement results of the vertical polarized wave components with the data stored in the database, and determines a first group of spots at which the wireless card might be situated. The control device also compares the measurement results of the horizontal polarized wave components with the data stored in the database, and determines a second group of spots at which the wireless card might be situated. The location of the wireless card is detected from the product set of the first group of spots and the second group of spots.
The conventional non-contact IC card reader/writer device 600 and the conventional non-contact IC card 610, however, only have data exchanging means. It is therefore necessary to employ a separate input device, so that a user can operate a device into which the non-contact IC card reader/writer device 600 is incorporated, such as an ATM.
An ATM is normally equipped with a touch panel as an input device. However, since such an input device is integrally formed with the screen of the ATM, it is necessary to lower the screen to a position in which an operator can easily operate the screen, or to raise the screen (the operating position) to a position in which an operator can easily view the screen. As a result, either the visibility or the operability of the screen is abandoned. With the technique disclosed in Japanese Unexamined Patent Publication No. 2000-46939, there is another problem that the production costs are even higher due to the database that is separately required.